tests: unset LD_PRELOAD in testsuite.service when it's run under ASan

This should help to address the "grep" issue we ran into in
https://github.com/systemd/systemd-centos-ci/pull/217.

man/repart.d.xml

@@ -1,7 +1,7 @@
 <?xml version='1.0'?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-<refentry id="repart.d">
+<refentry id="repart.d" conditional='ENABLE_REPART'>
 
   <refentryinfo>
     <title>repart.d</title>

man/rules/meson.build

@@ -49,7 +49,7 @@ manpages = [
  ['pam_systemd_home', '8', [], 'HAVE_PAM'],
  ['portablectl', '1', [], 'ENABLE_PORTABLED'],
  ['pstore.conf', '5', ['pstore.conf.d'], 'ENABLE_PSTORE'],
- ['repart.d', '5', [], ''],
+ ['repart.d', '5', [], 'ENABLE_REPART'],
  ['resolvectl', '1', ['resolvconf'], 'ENABLE_RESOLVE'],
  ['resolved.conf', '5', ['resolved.conf.d'], 'ENABLE_RESOLVE'],
  ['runlevel', '8', [], ''],
@@ -773,7 +773,7 @@ manpages = [
   'ENABLE_RANDOMSEED'],
  ['systemd-rc-local-generator', '8', [], ''],
  ['systemd-remount-fs.service', '8', ['systemd-remount-fs'], ''],
- ['systemd-repart', '8', ['systemd-repart.service'], ''],
+ ['systemd-repart', '8', ['systemd-repart.service'], 'ENABLE_REPART'],
  ['systemd-resolved.service', '8', ['systemd-resolved'], 'ENABLE_RESOLVE'],
  ['systemd-rfkill.service',
   '8',

man/systemd-repart.xml

@@ -3,7 +3,7 @@
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
 
-<refentry id="systemd-repart"
+<refentry id="systemd-repart" conditional='ENABLE_REPART'
     xmlns:xi="http://www.w3.org/2001/XInclude">
 
   <refentryinfo>

test/test-functions

@@ -469,9 +469,14 @@ printf "[Service]\nTimeoutSec=180s\n" >/etc/systemd/system/systemd-journal-flush
 # 1
 # Let's workaround this by clearing the previously set LD_PRELOAD env variable,
 # so the libasan library is not loaded for this particular service
-REMOUNTFS_CONF_DIR=/etc/systemd/system/systemd-remount-fs.service.d
-mkdir -p "\$REMOUNTFS_CONF_DIR"
-printf "[Service]\nUnsetEnvironment=LD_PRELOAD\n" >"\$REMOUNTFS_CONF_DIR/env.conf"
+unset_ld_preload() {
+    local _dropin_dir="/etc/systemd/system/\$1.service.d"
+    mkdir -p "\$_dropin_dir"
+    printf "[Service]\nUnsetEnvironment=LD_PRELOAD\n" >"\$_dropin_dir/unset_ld_preload.conf"
+}
+
+unset_ld_preload systemd-remount-fs
+unset_ld_preload testsuite
 
 export ASAN_OPTIONS=\$DEFAULT_ASAN_OPTIONS:log_path=/systemd.asan.log UBSAN_OPTIONS=\$DEFAULT_UBSAN_OPTIONS
 exec  $ROOTLIBDIR/systemd "\$@"